At least 24 deaths were caused by a massive storm, which has left about a million people without electricity across the U.S.'s midsection. But the forecast said another wintry blast was developing Wednesday over the southern Plains.
Ice ranging from a quarter-inch to an inch (2.5 centimeters) thick glazed roads in much of the central Plains and Midwest. At least 24 deaths have been blamed on the storm since it developed last weekend. Most resulted from traffic accidents.
Forecasters said more snow, sleet and freezing rain could develop across the northern Ohio Valley and from Pennsylvania into New England on Wednesday.
The power outage was the worst ever in Oklahoma, with more than 618,000 homes and businesses without electricity late Tuesday. Officials said it could be a week to 10 days before power is fully restored.
"We're relying on people to look after each other," Oklahoma City Mayor Mick Cornett said. "At the end of the day, this comes down to the strength of your people. ... People who have electricity ought to be sharing it with people who don't."
Elsewhere, nearly 350,000 customers were affected by outages in Missouri, Kansas, Iowa and Illinois.
The storm also caused extensive travel problems. More than 550 flights were canceled at Chicago's O'Hare Airport on Tuesday, and hundreds of other flights were delayed up to an hour by nighttime, said Chicago Department of Aviation spokesman Gregg Cunningham.
Officials in Missouri, Kansas and Oklahoma had declared states of emergency. President George W. Bush declared a federal emergency in Oklahoma on Tuesday, ordering government aid to supplement state and local efforts.
Cold rain was forecast to fall over parts of Oklahoma on Wednesday, but temperatures were expected to remain above freezing, said Patrick Burke, a weather service meteorologist in Norman, Oklahoma.
High temperatures should reach the 40s (about 4-6 Celsius) on Thursday with no additional rainfall expected, Burke said. But by late Friday, another storm could bring 2 to 4 inches (5-10 centimeters) of snow to some areas , he said.
The 24 deaths blamed on the weather include 15 in Oklahoma, four in Kansas, three in Missouri and one each in Nebraska and Michigan.